JP5262829B2 - Developing apparatus and developing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the development defect by forming a liquid film of developer over the entire surface of a wafer W even if the water repellency of the surface of the wafer W is high when development is carried out by discharging the developer to the surface of the rotating wafer W. <P>SOLUTION: In a state where the wafer W held on a spin chuck 11 is rotating, the developer is discharged from a developer nozzle 30 to the wafer W while moving the developer nozzle 30 from above the peripheral part of the wafer W to above the central part thereof. A liquid pool of developer is formed in the center of the wafer W by setting the number of revolutions of the wafer W to low-speed rotation of 100 rpm, for example, when the developer nozzle 30 is arranged above the central part of the wafer W. Thereafter, the number of revolutions of the wafer W is set to high-speed rotation of about 2,000 rpm, for example, in order to spread the liquid pool of developer instantaneously over the entire surface of the wafer W. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a developing method and a developing apparatus for performing a developing process on a substrate after a resist solution is applied and subjected to an exposure process.

  Conventionally, in a photoresist process, which is one of semiconductor manufacturing processes, a resist is applied to the surface of a semiconductor wafer (hereinafter referred to as a wafer), which is a substrate, the resist is exposed in a predetermined pattern, and then developed to develop a resist. A pattern is formed. Such processing is generally performed using a system in which an exposure apparatus is connected to a coating / developing apparatus that performs resist coating / development.

By the way, in the development processing method, the wafer is held by a spin chuck which is a substrate holding unit, the wafer is rotated about the vertical axis, and the developer nozzle is moved from the peripheral portion of the wafer to the center portion while developing the developer nozzle. There is a method of performing development processing by discharging more developer (see Patent Document 1). The method will be specifically described with reference to FIG. 11. First, a pretreatment liquid is applied at a wafer rotation speed of, for example, 1000 rpm (time t ₀ ), the wettability of the wafer surface is improved, and a developer to be applied later Prepare an easy-to-expand environment (pre-wet process). Next, the developing solution is discharged while moving the developing solution nozzle from the peripheral edge of the wafer to the center (time t ₁ ), and the developing solution is spirally spread by the centrifugal force of the rotating wafer, and is applied to the surface of the wafer. A liquid film of a developer is formed. At this time, the rotation speed of the wafer is, for example, 1000 rpm. Thereafter, the discharge of the developing solution is stopped (time t ₂ ), and the developing solution is held on the surface of the wafer by reducing the number of rotations of the wafer to, for example, 50 rpm, and the developing process is performed. Then, after the developing process, a cleaning solution is supplied to the wafer to wash away the developing solution, and spin drying is performed.

  On the other hand, an exposure machine is known that performs immersion exposure in which a liquid film of pure water is exposed on the surface of a wafer in order to increase exposure resolution. In this immersion exposure, the surface of the wafer to be exposed is contacted with, for example, water with high water repellency in order to improve the followability of scanning of the exposure unit immersion part (lens tip) and ensure the same throughput as that of a conventional exposure apparatus. Consider forming a protective film with an angle of about 80 to 85 degrees, or forming a resist film using a resist having a high water repellency, for example, a contact angle of water of 85 degrees or more without forming a protective film. Has been. The contact angle is an angle formed between a tangent line on the surface of the substrate and the surface of an arc that forms the outer edge of the water droplet in the cross section of the water droplet when the water droplet is attached to the surface of the wafer.

  In the developing method described above, the developer D discharged to the center position of the wafer W spreads due to centrifugal force as shown in FIG. 12A, but the liquid film becomes thinner toward the periphery of the wafer W. Therefore, when the surface of the wafer W has high water repellency, it becomes difficult to spread uniformly, and as shown in FIG. 12B, an exposed portion B in which the liquid film of the developing solution D is not formed may occur near the periphery of the wafer. is there. Even if a liquid film of the developer D is formed on the entire surface of the wafer, there is a possibility that the liquid film may be broken by the surface tension before the cleaning process is started. As a result, there is a problem that development defects are likely to occur due to the presence of the portion B where the surface is exposed without forming a liquid film. Further, if the surface of the wafer W has a high water repellency, when the developer D is discharged onto the wafer, the discharged developer D rebounds from the surface of the wafer, causing contamination of the developer nozzle, and the inside of the developing device. There is a risk of causing particles.

JP2005-210059

  The present invention has been made under such circumstances, and when applying a developer to the surface of a rotating substrate, the entire surface of the substrate is covered even if the surface of the substrate is highly water-repellent. Another object of the present invention is to provide a developing method and a developing apparatus that can form a liquid film of a developer and reduce development defects.

The developing method according to the present invention is a developing method in which the developer is discharged from the developer nozzle to the substrate while rotating the substrate held by the substrate holder.
The developer nozzle is operated so that the discharge position of the developer moves from the peripheral portion of the substrate to the central portion while rotating the substrate at the first rotation speed and discharging the developer from the developer nozzle. Process,
Next, in a state where the developer is discharged to the central portion of the substrate, the rotational speed of the substrate is set to a second rotational speed lower than the first rotational speed in order to form a liquid pool at least in the central portion of the substrate. Rotating, and
Then, the substrate is rotated at a third rotational speed higher than the second rotational speed to spread the developer on the surface of the substrate.

The developing method according to the present invention may take the following configuration.
The said board | substrate is the structure whose water contact angle of the surface is 85 degree | times or more.
The first rotation speed is 500 to 1500 rpm.
The second rotation speed is 50 to 500 rpm.
The third rotation speed is 1000 to 2500 rpm.

The developing device according to the present invention is a developing device that discharges the developer from the developer nozzle to the substrate while rotating the substrate held by the substrate holder.
A substrate holder for holding the substrate;
A rotation drive unit that rotates the substrate holding unit around a vertical axis;
A developer nozzle for applying a developer to the substrate held by the substrate holder;
An operation mechanism for operating the developer nozzle;
The developer nozzle is operated so that the discharge position of the developer moves from the peripheral portion of the substrate to the central portion while rotating the substrate at the first rotation speed and discharging the developer from the developer nozzle. Steps,
Next, in a state where the developer is discharged to the central portion of the substrate, the rotational speed of the substrate is set to a second rotational speed lower than the first rotational speed in order to form a liquid pool at least in the central portion of the substrate. A rotating step;
And a step of rotating the substrate at a third rotational speed higher than the second rotational speed to spread the developer on the surface of the substrate, and a controller that outputs a control signal to perform It is characterized by that.

  According to the present invention, when supplying the developing solution from the developing solution nozzle to the central portion of the substrate, the number of rotations of the substrate is lowered, thereby forming a liquid pool at least in the central portion of the substrate, and then increasing the number of rotations of the substrate. doing. For this reason, at least the liquid stored in the central part spreads by high-speed rotation, so the liquid film goes to the peripheral part in a thick state, so that even if the water repellency of the substrate surface is high, it tends to spread evenly, and development defects occur. Can be suppressed. In addition, if a liquid pool that can be spread sufficiently uniformly when rotating at high speed is formed at low speed, and then the liquid is transferred to high speed without spreading to the peripheral edge at low speed, the throughput decreases. Can be suppressed as much as possible.

1 is a longitudinal sectional view of a developing device according to an embodiment of the present invention. FIG. 2 is a plan view of the developing device. FIG. 3 is a perspective view of a developer nozzle used in the developing device. It is a schematic diagram of the control part which controls the said developing device. It is explanatory drawing explaining the rotation speed of a wafer, and the timing of supply of a developing solution. It is the schematic diagram which showed typically a mode that the developing solution nozzle moved. It is the schematic diagram which showed typically a mode that the developing solution was supplied to a wafer. 1 is a plan view showing a coating / developing apparatus in which a developing apparatus according to an embodiment of the present invention is incorporated. It is a perspective view of the coating / developing apparatus. It is a longitudinal cross-sectional view of the said coating / developing apparatus. It is a conventional developer supply recipe associated with the number of rotations of a wafer. It is a schematic diagram which shows typically a mode that the wafer based on the supply recipe of the conventional developing solution is coat | covered with a developing solution.

  An embodiment of the developing method according to the present invention will be described. FIG. 1 and FIG. 2 are views showing a developing device for carrying out this embodiment, and this developing device has a spin chuck 11 which is a substrate holding portion for sucking and holding a substrate, for example, a wafer W, in the center. The spin chuck 11 is connected to a rotation driving unit 13 that is a motor, for example, provided below the rotation shaft 12 and can rotate around the vertical axis while holding the wafer W, and can also move up and down. It is possible. The developing device is provided with a cup body 20 so as to surround the wafer W held by the spin chuck 11. The cup body 20 includes an outer cup 21 and an inner cup 22, and the upper side of the cup body 20 is open. The outer cup 21 has a quadrangular shape on the upper side and a cylindrical shape on the lower side. A step portion 23 is formed at the lower end portion of the outer cup 21. Furthermore, the outer cup 21 can be moved up and down by a lifting unit 24 provided below. The inner cup 22 is cylindrical, and the upper side is inclined inward. Further, the lower end surface of the inner cup 22 is pushed upward when it comes into contact with the stepped portion 23 when the outer cup 21 is raised or lowered.

  A circular plate 25 is provided on the lower side of the wafer W held by the spin chuck 11, and a guide member 26 having a mountain shape in the longitudinal section is provided outside the circular plate 25. The guide member 26 guides the developer and cleaning liquid spilled from the wafer W to a liquid receiving portion 27 described later. A liquid receiving portion 27 having a longitudinal section formed on the concave portion is provided on the outer side of the circular plate 25 over the entire circumference. A waste liquid pipe 28 is connected to the bottom surface of the liquid receiving portion 27 from below. Although not shown, the waste liquid pipe 28 is connected to a waste liquid tank, and a gas-liquid separator is provided in the middle thereof to separate exhaust and waste liquid. Although not shown, the developing device is provided with, for example, three elevating pins that penetrate the circular plate 25 from below, and these elevating pins spin the wafer W by cooperation with a substrate transfer arm (not shown). It can be transferred to the chuck 11.

  Further, the developing device is provided with a developing solution nozzle 30 and a cleaning solution nozzle 40 above the wafer W held by the spin chuck 11. As shown in FIG. 3, the developer nozzle 30 is provided with a belt-like discharge port 30a having a length L1 of 8 to 15 mm and a width L2 of 0.1 to 1 mm, for example.

  The developer nozzle 30 is connected via a developer supply pipe 31 to a developer supply system 54 including a developer supply source 32 and a solution supply control device (valve, pump, etc.). Further, as shown in FIG. 2, the developer nozzle 30 is supported by one end of a nozzle arm 33 which is a support member, and the other end of the nozzle arm 33 is connected to the moving base 34 via a lifting mechanism (not shown). Yes. The moving base 34 can move along a guide rail 35 extending in the X direction. In the figure, reference numeral 36 denotes a standby portion of the developer nozzle 30, and the standby portion 36 cleans the tip of the developer nozzle 30.

  The cleaning liquid nozzle 40 is a nozzle for discharging a cleaning liquid such as pure water to the wafer W, and is connected to a cleaning liquid supply system 55 including a cleaning liquid supply source 42 and a cleaning liquid supply control device (valve, pump, etc.) via a cleaning liquid supply pipe 41. It is connected. As shown in FIG. 2, the cleaning liquid nozzle 40 is supported by one end of a nozzle arm 43 and is connected to a moving base 44 through an elevating mechanism (not shown). The moving base 44 is X along the guide rail 35. It can move in the direction. In the figure, reference numeral 45 denotes a standby portion of the cleaning liquid nozzle 40.

  FIG. 4 shows a control unit 50 for controlling each unit of the developing device. The control unit 50 is a computer including a CPU 51, a program 52a stored in a program storage unit 52, a data bus 53, and the like. The program 52a controls the rotation drive unit 13, the developer supply system 54, the cleaning liquid supply system 55, and the nozzle drive system 56 based on the process recipe.

  Next, a method for developing the wafer W using the above-described developing device will be described. A wafer having a high water repellency, for example, a static contact angle of water of 85 degrees or more is applied to the surface of the wafer W carried into the developing device by the coating device, and immersion exposure is performed by the exposure device. Yes. First, with the outer cup 21 and the inner cup 22 of the developing device positioned downward, the wafer W is transferred into the developing device by a transfer arm (not shown). The wafer W is placed on the spin chuck 11 by the cooperative action of the transfer arm and the lift pins, and is sucked and held.

Next, a process of operating the developer nozzle 30 so that the developer discharge position moves from the peripheral edge to the center of the wafer W while rotating the wafer W at the first rotation speed will be described. As shown in FIG. 5, the wafer W is rotated at a first rotation number, for example, 500 rpm, and the developer nozzle 30 is arranged so that the length direction of the discharge port 30 a coincides with the line connecting the central portion and the peripheral portion of the wafer W. For example, the wafer W is disposed above the peripheral edge of the wafer W so as to coincide with the radial direction of the wafer W (see FIG. 6), and the developer is discharged onto the wafer W (time t _{0 in} FIG. 5). The discharged developer is spread by the centrifugal force generated by the rotation of the wafer W. The developer nozzle 30 is moved above the central portion of the wafer W while the developer is being discharged (see FIG. 6). The time required to move the developer nozzle 30 from the upper edge of the wafer W to the upper center is, for example, about 1 second. Thus, the developer nozzle 30 is moved from above the peripheral edge of the wafer W to above the central portion, and the developer is discharged in a strip shape from the discharge port 30a. Can be applied, and development processing is performed at the portion where the developer is applied.

Next, when the developer nozzle 30 moves to above the center of the wafer W (time t _{1 in} FIG. 5), the number of rotations of the wafer W is reduced to a second number of rotations, for example, 100 rpm, and for example, the developer continues for 2 seconds. Is discharged. Then, while the developer D is being supplied to the center of the wafer W, the rotation speed of the wafer W is increased to a third rotation speed higher than the second rotation speed, for example, 2000 rpm (time t _{2 in} FIG. 5). ), For example, the supply of the developer D is stopped after 10 seconds. Immediately thereafter, the wafer W is decelerated at a speed of, for example, 20000 rpm / s, and dropped to a fourth rotational speed, for example, 50 rpm (time t _{3 in} FIG. 5), and the developer nozzle 30 is retracted to the standby unit 36. . This fourth rotational speed is sufficient to make the peripheral edge of the developing solution D be formed at the peripheral edge of the wafer W without being pulled back to the central part of the wafer W by its surface tension. For example, the wafer W is rotated at the fourth rotation number for about 2 seconds, and then the rotation of the wafer W is stopped for 45 seconds, for example.

  Thereafter, the cleaning liquid is discharged from the cleaning liquid nozzle 40 to the center of the wafer W. At this time, the rotation speed of the wafer W is, for example, 500 rpm, and the discharged cleaning liquid is spread from the center of the wafer W toward the peripheral edge, so that the developer D is cleaned. Thereafter, the supply of the cleaning liquid is stopped, the cleaning liquid nozzle 40 is retracted to the standby unit 45, the outer cup 21 and the inner cup 22 are raised by the elevating mechanism, and the wafer W is spin-dried for a predetermined time at a rotation speed of 2000 rpm, for example. Let Thereafter, the wafer W is unloaded from the developing device by the transfer arm and the developing process is completed.

  As described above, when the developer nozzle 30 is positioned above the central portion of the wafer W, the discharged developer D is discharged from the wafer W by setting the rotation speed of the wafer W to a low-speed rotation of, for example, about 100 rpm. Although it gradually spreads outward due to the centrifugal force, a liquid pool is formed in the central portion of the wafer W because of the low-speed rotation (FIG. 7A). Thereafter, the rotation speed of the wafer W is set to, for example, a high-speed rotation of 2000 rpm, so that the wafer W is spread at a stretch by a large centrifugal force. However, since a liquid reservoir exists in the central portion, the amount of the liquid film source spreading is large. For this reason, since the liquid film is thick, even if the water repellency of the surface of the wafer W is high, the liquid film is not easily interrupted and spreads uniformly from the center part to the peripheral part of the wafer W (FIG. 7B). Further, a part of the developer D spills outward from the periphery of the wafer W, but flows along the guide member 26 described above, is temporarily stored in the liquid receiver 27, and is developed from the waste liquid pipe 28. It is discharged outside.

  Since the second rotational speed is a rotational speed for forming a pool of the developer D at the center of the wafer W, if the rotational speed is too high, the centrifugal force of the wafer W increases, and the developer The discharge cannot catch up and no liquid pool is formed. On the other hand, if the second rotational speed is too low, the liquid film already formed on the surface of the wafer W is broken, so 50 to 500 rpm is preferable, and 50 to 200 rpm is more preferable. Further, the time during which the wafer W is rotated at the second number of rotations may be longer than the time sufficient for the liquid pool to be formed in the central portion of the wafer W. Even if this time is long, there is no effect on the processing, but if a liquid pool is formed at the center, there is no need to maintain low-speed rotation thereafter. Thus, it is preferable to increase to the third rotation number after 1 second (shift to high-speed rotation). Therefore, it can be said that the present invention requires that a liquid pool be formed at least in the central portion of the wafer W.

  The third rotational speed is a rotational speed for instantly spreading the developer D (liquid reservoir) to the peripheral edge of the wafer W. The reason why the liquid pool is instantly expanded is that when the surface of the wafer W has a high water repellency, for example, a contact angle of 85 degrees, the surface of the wafer W has a high drying rate and is easily dried. This is because if a long time is taken to spread the film, the liquid film is partially dried, torn off, and does not spread uniformly. Therefore, the instant here means that the rotation speed is shifted to the third rotational speed as quickly as possible to ensure that the liquid pool in the central portion of the wafer W spreads uniformly.

  According to the above-described embodiment, the developing solution D is discharged from the developing solution nozzle 30 to the central portion of the wafer W when performing the development by rotating the wafer W while moving the developing solution discharge position from the peripheral portion to the central portion. In doing so, the wafer W is set to a low second rotation speed, and a liquid pool of the developer D is formed at least in the center of the wafer W. Thereafter, the wafer W is set to a high-speed third rotational speed, and the developer D stored in the central portion spreads to the peripheral portion with the liquid film being thick, so even if the surface of the wafer W has high water repellency. It is easy to spread uniformly, and the occurrence of development defects can be suppressed. Further, after a liquid pool is formed at a low speed rotation (second rotation speed) that can spread sufficiently uniformly when the rotation speed is high speed (third rotation speed), the liquid is discharged to the peripheral portion by low speed rotation as it is. If it shifts to high speed rotation without spreading it, it is possible to suppress a decrease in throughput as much as possible.

  Next, an example of a coating and developing device to which the developing device of the present invention is applied will be briefly described. FIG. 8 is a plan view of the coating and developing apparatus, and FIG. 9 is a perspective view of the coating and developing apparatus. In this apparatus, a carrier block S1 is provided. In this block S1, the transfer arm C takes out the wafer W from the hermetically sealed carrier 100 mounted on the mounting table 101 and is adjacent to the block S1. In addition, the transfer arm C is configured to receive the processed wafer W processed in the process block S2 and return it to the carrier 100.

  As shown in FIG. 9, the processing block S2 is a first block (DEV layer) B1 for performing development processing in this example, and a processing for forming an antireflection film formed on the lower layer side of the resist film. The second block (BCT layer) B2, the third block (COT layer) B3 for applying the resist solution, and the antireflection film forming process formed on the upper layer side of the resist film. 4 blocks (TCT layers) B4 are stacked in order from the bottom.

  The second block (BCT layer) B2 and the fourth block (TCT layer) B4 are respectively a liquid processing apparatus for applying a chemical solution for forming an antireflection film by spin coating, and this liquid processing apparatus. A heating / cooling system processing unit group for performing pre-processing and post-processing of the processing to be performed, and a transfer arm that is provided between the coating processing apparatus and the processing unit group and delivers the wafer W between them. A2 and A4 are provided. The third block (COT layer) B3 has the same configuration except that the chemical solution is a resist solution and a hydrophobic treatment unit is incorporated. On the other hand, for the first processing block (DEV layer) B1, for example, the developing units of the present invention are stacked in two stages in one DEV layer B1. In the DEV layer B1, a common transfer arm A1 for transferring the wafer W to the two-stage development units is provided. Further, as shown in FIG. 8 and FIG. 10, the processing block S2 is provided with a shelf unit U1, and between each part of the shelf unit U1, a transfer arm that can be raised and lowered is provided in the vicinity of the shelf unit U1. The wafer W is transferred by D1.

  In such a coating and developing apparatus, the wafer W from the carrier block S1 is sequentially transferred by the transfer arm C to one transfer unit of the shelf unit U1, for example, the corresponding transfer unit CPL2 of the second block (BCT layer) B2. From here, the wafer W is transferred into the third block (COT layer) B3 via the transfer unit CPL3 and the transfer arm A3, and the wafer surface is hydrophobized in the hydrophobizing unit, and then the liquid processing apparatus 2 A resist film is formed. The wafer W after the formation of the resist film is transferred to the transfer unit BF3 of the shelf unit U1 by the transfer arm A3.

  Thereafter, in this case, the wafer W is transferred to the transfer arm A4 via the transfer unit BF3 → the transfer arm D1 → the transfer unit CPL4, and after the antireflection film is formed on the resist film, the transfer arm A4 transfers the wafer W. Passed to TRS4. In some cases, an antireflection film is not formed on the resist film, or an antireflection film is formed in the second block (BCT layer) B2 instead of performing the hydrophobic treatment on the wafer W.

  On the other hand, on the upper part in the DEV layer B1, a shuttle arm E which is a dedicated transfer means for directly transferring the wafer W from the transfer unit CPL11 provided in the shelf unit U1 to the transfer unit CPL12 provided in the shelf unit U2. Is provided. The wafer W on which the resist film and further the antireflection film are formed is delivered to the delivery unit CPL11 by the delivery arm D1 via the delivery units BF3 and TRS4, and from here to the delivery unit CPL12 of the shelf unit U2 directly by the shuttle arm E. It is conveyed and taken into the interface block S3. The delivery unit with CPL in FIG. 10 also serves as a cooling unit for temperature control, and the delivery unit with BF also serves as a buffer unit on which a plurality of wafers W can be placed. Yes.

  Next, the wafer W is transferred to the exposure apparatus S4 by the interface arm B, and after being subjected to immersion exposure processing, it is placed on the transfer unit TRS6 of the shelf unit U2 and returned to the processing block S2. The returned wafer W is developed in the first block (DEV layer) B1, and is transferred by the transfer arm A1 to the transfer table in the access range of the transfer arm C in the shelf unit U5. And returned to the carrier 100. In FIG. 8, U3 is a processing unit group in which a heating unit and a cooling unit are stacked.

W Wafer 11 Spin chuck 13 Rotation drive unit 20 Cup body 30 Developer nozzle 30a Discharge hole 32 Developer supply source 40 Cleaning solution nozzle 42 Cleaning solution supply source 50 Control unit 52a Program 56 Nozzle drive system D Developer

Claims (6)

In the developing method of discharging the developer from the developer nozzle to the substrate while rotating the substrate held by the substrate holder,
The developer nozzle is operated so that the discharge position of the developer moves from the peripheral portion of the substrate to the central portion while rotating the substrate at the first rotation speed and discharging the developer from the developer nozzle. Process,
Next, in a state where the developer is discharged to the central portion of the substrate, the rotational speed of the substrate is set to a second rotational speed lower than the first rotational speed in order to form a liquid pool at least in the central portion of the substrate. Rotating, and
And a step of rotating the substrate at a third rotational speed higher than the second rotational speed to spread the developer on the surface of the substrate.   The developing method according to claim 1, wherein a contact angle of water on the surface of the substrate is 85 degrees or more.   The developing method according to claim 1, wherein the first rotation speed is 500 to 1500 rpm.   The developing method according to claim 1, wherein the second rotational speed is 50 to 500 rpm.   The developing method according to claim 1, wherein the third rotation speed is 1000 to 2500 rpm. In the developing device for discharging the developer from the developer nozzle to the substrate while rotating the substrate held by the substrate holder,
A substrate holder for holding the substrate;
A rotation drive unit that rotates the substrate holding unit around a vertical axis;
A developer nozzle for applying a developer to the substrate held by the substrate holder;
An operation mechanism for operating the developer nozzle;
The developer nozzle is operated so that the discharge position of the developer moves from the peripheral portion of the substrate to the central portion while rotating the substrate at the first rotation speed and discharging the developer from the developer nozzle. Steps,
Next, in a state where the developer is discharged to the central portion of the substrate, the rotational speed of the substrate is set to a second rotational speed lower than the first rotational speed in order to form a liquid pool at least in the central portion of the substrate. A rotating step;
And a step of rotating the substrate at a third rotational speed higher than the second rotational speed to spread the developer on the surface of the substrate, and a controller that outputs a control signal to perform A developing device.

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